Top ISNR Manufacturing Company

PRODUCTS GRADES

The group manufactures various grades of ISNR (ISNR-20) from field coagulum which has much demand in tyre sector. We have taken atmost effort to maintain the quality of the product. ISNR is used in the manufacturing of various products like automotive bushes, molded goods, tyre and tubes, and engineering goods. PTR equipped with huge production capacity and infrastructure that could meet the increasing demands in the market.

The following table shows the Physical and Chemical Requirements for Technically Specified Rubber;

Characteristics	REQUIREMENTS FOR DIFFERENT GRADES FOR I.S.N.R.
	3CV	3L	5	10	20	50
Dirt Content (% by mass, max)	0.03	0.03	0.05	0.10	0.20	0.50
Volatile Matter (% by mass, max)	0.80	0.80	0.80	0.80	0.80	0.80
Ash (% by mass, max)	0.50	0.50	0.60	0.75	1.00	1.50
Nitrogen (% by mass,max)	0.60	0.60	0.60	0.60	0.60	0.60
Initial Plasticity (Po)min	40+5	30	30	30	30	30
Plasticity Retention Index (PRI) min	60	60	60	60	60	60

CONTENT	ISNR 20
Dirt content	0.2 % max.
P0	30 min.
PRI	40 min.
Volatile Matter	0.8 %max.
Ash Content	1.0 %max.
Nitrogen Content	0.6 %max.

ISNR-20

It is a large volume grade of technically specified natural rubber. It is produced mostly from field coagulam, with lower grades of RSS and or unsmoked sheets.General characteristics of ISNR-20 as follows:

Excellent processing characteristics and good physical properties.
Low viscosity and easier mixing characteristics will reduce the mastication and mixing period considerably.

Uses:

Tyres
Cushion gum stocks
Bicycle tyres
Raincoat proofings
Microcellular sheets for upholstery and packing
Conveyor belts , foot wears and other general products

MANUFACTURING PROCESS

Raw materials are scrap rubber available from the open market, rubber plantation/ estate or through different traders and agents. Raw materials are available throughout the year from traders, farmers, estates etc. Imported scraps rubber raw materials are available in the open market. The latest study reveals that more than 50% area of cultivation in Tripura is rubber plants. More over there are very few crumb rubber units are operating due to lack of technical knowhow and financial stability. So the surplus production are sold to nearby states. Hence availability of raw materials is not at all a constraint.

The process and production technologies described as follows:

An optimum production of 9000 MT crumb rubber annually on a three shift basis. Keeping in view energy efficient operation, continuous three shift operation of the factory is considered as advantageous. By working on three shift basis, number of preheating of dryer can be reduced to the minimum.

The technical experts from rubber board, and on the experience from the operation of two similar units, the capacity of the unit is fixed as 30 MT per day. Standard equipments to achieve this capacity are available indigenously.

The raw material mainly consists of cup lumps and tree laces are stored in a place where further contamination is prevented. The first step for the processing is manual sorting of row material and this will help to remove degraded rubber, foreign materials etc. The sorted lump rubber is first fed into a slab cutter through a belt conveyer to reduce the bigger size lumps into smaller ones. Later this material is put into a blending tank for initial washing. A retention period of four hours will be maintained in this blending tank. Later the material from this tank is fed into either pre-breaker1 or 2 which are kept parallel. Bucket elevators 1 and 2 are used to transfer the material from the blending tank to the respective pre-breaker. Pre-breaker consists of two scrolls cutting each other to obtain lacy crepes. This is put into a large blending tank for initial removal of dirt.

The raw material from the blending tank is sent to the hammer mill-1 through a bucket elevator. The hammer blades will cut the rubber into small crumbs measuring about 5 to 8 mm in size. While the crumbs are formed, the embedded dirt gets exposed. Along with the dirt, the crumb fall into a blending tank where the crumb floats on the surface and the dirt being denser sinks to the bottom. Water is kept agitated to ensure better washing. Agitation is achieved by impellers and water jet system. The flow of water is maintained from the tank to the crumb collection point by recycling the water back to the tank by a separate pump which in turn moves the floating crumb to the next bucket elevator. A mechanical agitator is also provided in the blending tank for agitation.

Then the material is fed into the creeper-1 with the help of bucket elevators. Creepers are ordinary rubber mill roller mills with diamond shape grooves running across the rolling surface. Because of the high pressure exerted by the rollers and the relative movement between the rollers the cup lumps and tree laces are stretched and exposes the dirt pores. While passing through the creepers the small sized crumbs will be converted into a blanket form which will be transferred to the creeper-2 through belt conveyer. In creeper-2, the same process is repeated. By passing through the creeper-2 , better size reduction and dirt removal is achieved. Wash water is provided in both the creepers.

The raw rubber from the creeper-2 is then fed into hammer mill-2 through a conveyer. In hammer mill-2, the process is repeated as in hammer mill-1, but better size reduction is achieved. Average size of crumb coming out of hammer mill-2 is 4 to 6 mm. Crumb from this mill falls into a blending tank where agitators and water jets are provided, similar to the blending tank of previous hammer mill. Water jets direct the floating crumbs to the collection location of next bucket elevator.

Rubber from the blending tank of Hammer Mill-2, is then fed into the Creeper-3, with the help of bucket elevator. Rollers of Creeper-3 convert the small sized crumb particles into blanket during the milling operation. The blanket formed in creeper 3 is then passed through creeper 4, 5 and 6, where all, the processes is repeated as in previous creepers. In each pass through Creepers, shearing and cleaning of rubber gets improved. Wash water is provided in all Creepers.

Rubber which is in the form of blanket from creeper-6 is then fed into Shredder. The Shredder again cut the rubber into fine crumbs. The rate of feeding is controlled by a variable speed feed rollers. The crumbs are collected in the final blending tank for washing. At this stage the entire dust have been removed. From the final blending tank, the crumbs are collected to the drier trolleys using crumb collection pump and vibration system to reduce the moisture content and load in the drier. The trolley with crumbs will be ready for feeding into the drier.

The drying process is very slow and round the clock operation. The crumbs collected from the washing tank are filled into the drier trays which are made of steel sheets with perforated bottom. The drier proposed is conveyorised counter flow tunnel type, in which the slow movement of conveyor takes the box through three zone of drying. The drier is heated by flue gases from the combustion of natural gas. The blower system delivers hot air to the various zone through a diverging type distributor connection. In the last zone of the drier air enters through the bottom of trolley and exit at the top. In this zone the crumb is almost dry and in well heated condition. Drier temperature in this zone is in the range of 100 oC to 105 oC. Therefore heat potential difference and loss of heat will be minimum. In the first zone the hot air carries out two parameters 1) to remove the sticking droplets, 2) heating the crumb to the temperature of second zone. The exit air from the zone 1 is moisture laden and hence cannot be reused completely. However a part of the hot air is re-circulated into the heater for the conservation of energy. Usually it takes 4 - 4.5 hours to dry the product inside the drier after feeding the box at the inlet. Last zone in the drier is cooling zone, where the crumb is cooled using fans and blowers. The product coming out of the drier is left exposed for some more time for cooling.

The cooled product is passed through a Metal Detector for the inspection of any metal parts. This is very essential now days as tyre companies are insisting to examine whether any metal parts like stapler pins, bolts etc. are embedded in rubber.

For easy transportation and handling and to reduce the space for storage, the dried crumbs are compressed to bring down to a manageable size and shape and to prevent further trapping of dirt. This is carried out with high speed single chamber up stroke hydraulic bailing press. The product from the press is packed in polythene sheets and LDPE blown bags. Samples are taken from the blocks for final analysis to confirm quality. The bale weighs 25 kg each.

Products

Indian Standard Natural Rubber

Manufacturing Process

PRODUCTS GRADES

ISNR-20

MANUFACTURING PROCESS

TOP ISNR MANUFACTURER

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